1. Field of the Invention
The present invention relates to a technique for creating color profiles.
2. Description of the Related Art
Recently, in addition to personal computers, peripheral devices such as color printers, digital cameras, and digital video devices, as well as digital video systems such as monitors and projectors have spread remarkably. Regarding printers, in particular, as the printers have become more sophisticated, they have been used for diverse purposes, while at the same time there has been growing user demand for color matching.
In the print industry, there are thousands of print-media types, with types of material, color tone, gloss, and the like increasing steadily year by year. Among other things, many of the media recently available on the market contain special paints known as fluorescent brighteners to make the media look whiter to the human eye than the intrinsic color tones of the material. Generally, fluorescent brighteners have the property of absorbing light of short wavelengths in the visible to ultraviolet wavelength regions and releasing light on the longer-wavelength side.
Thus the fluorescent brightener, when used in paper, has the effect of causing the white color of the paper to be perceived by the human eye as a white color brighter than the intrinsic color of the paper. On the other hand, in precise color matching done using a color profile or the like, the fluorescent brightener can pose a major problem depending on its amount or characteristics.
The problem stems from changes in apparent spectral reflectance caused by differences between the light source used for measurement and the light source in a viewing environment. Consequently, there is a problem in that if a color profile of a medium containing a fluorescent brightener is created using a typical method, a printed image will not agree with subjective perception, generally showing a strong tinge of yellow.
Techniques proposed to solve the problem include those disclosed in Japanese Patent Laid-Open Nos. 2001-174334 and 2002-139381. First each of the two techniques takes measurements using a special filter which cuts off a short wavelength region. Next the technique takes measurements without the filter. Then the technique calculates a correction factor based on information about the differences between the two types of measurement and makes corrections at an XYZ value level.
However, the conventional techniques described above need to take measurements both with and without the special filter which cuts off a short wavelength region, using different methods. This can cost time. Also, because of the need for a high-precision filter, the techniques cost money and lack versatility and cannot be used generally. Furthermore, since XYZ values are used for all corrections, the techniques provide lower accuracy than methods which use spectral data.